The technology of cancer therapy has been advanced in recent years. Remarkable advances have been made not only in conventional sugical operations but also in chemotherapy, radiotherapy and immunotherapy. However, the advantages of chemotherapy and radiotherapy in particular are liable to be accompanied by severe side effects.
The ideal chemotherapeutic agent is such that it displays a carcinostatic effect but little or no adverse affect on normal tissues. However, since conventional chemotherapeutic agents induce strong inhibition of the bone marrow accompanied by decreases in leukocytes and platelets, it is impossible to administer them consecutively over a long period, and the medication must be interrupted due to these side effects. The irradiation of X-ray or .gamma.-ray for radiotherapy likewise causes adverse effects on hematogenic tissues such as the bone marrow. Particularly if leukocytes, platelets, etc. are markedly decreased, the irradiation should be discontinued.
Transfusion is one of the conventional methods of inhibiting or ameliorating reductions in platelets, etc. which serve as dose-limiting factors. However, since blood cells such as platelets and leucocytes have a short life, fresh blood cells should be frequently replenished with. When bone marrow disorder is severe, bone marrow transplantation should be performed. Such bone marrow transplantation is intended to transfer hematogenic stem cells of the bone marrow to the body and thus to produce platelets in the body. This method has afforded an epochal effect in therapy for certain types of tumors and thus established a fundamental therapy for malignant tumors. However, the above bone marrow transplantation has problems as follows:
It is very difficult to supply donors of bone marrow fitting to patients. Even if a donor is supplied, the transplantation operation is difficult and it generally takes several weeks for the bone marrow transplanted to take, commence hematogenesis and then produce leukocytes, platelets, etc. in peripheral blood. During this period, the patient therefore may hover between life and death.
As described above, although transfusion and bone marrow transplantation are methods for ameliorating decreases in platelets and like side effects which occur in chemotherapy, radiotherapy or like therapy for cancer, bone marrow transplantation has various problems. In order to overcome such problems, patients themselves should have an improved hematogenic function. Therefore it is desired in the pharmaceutical field to develop a novel medicament having activity to promote hematogenesis. Particularly a medicament having activity to promote production of platelets is totally unknown.